Method of making motor-vehicle tires



E. HOPKINSDN.

METHOD OF MAKING MOTOR VEHICLE TIRES. APPLICATION FILED JAN. 4. 1917.

Patented Apr. 12, 1921.

7 SHEETS-SHEET I.

Inventor:

E. HOPKINSON.

METHOD OF MAKING MOTOR VEHICLE TIRES.

APPLICATION FILED JAN-4 1917 1,374,505, Patented Apr. 12, 1921.

I SHEETS-SHEET 2- A ttest: Inventor:

4. 1917. 1,374,505, Patented Apr. 12, 1921.

EETS-SHEET 3.

E. HUPKINSON METHOD OF MAKING MOTOR VEHICLE TIRES.

APPLICATION FILED JAN. 4. I917- Patented Apr. 12, 1921.

7 SHEETS-SHEET 4.

In ventor:

A ttest E. HOPKINSON. METHOD OF MAKING MOTOR VEHICLE TIRES.

APWICATION FILED JKN4. I917- E. HOPKINSON. METHOD OF MAKING MOTORVEHICLE TIRES.

AP LICATION FILED JAN-4,1917- Patented Apr. 12, 1921.

7 SHEETSSHEET 5.

In ventor:

A ttest:

EEEEEEEEEE N.

TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT s.

M LiLATION HLLD JAN. 4. 1917. 1,374,505. Patented Apr. 12,1921.

7 SHEETS- EEEEE 7.

UNITED STATES ERNEST HOPKINSON, OF NEW YORK,' N. Y.

METHOD OF MAKING MOTOR-VEHICLE TIRES.

Specification of Letters Patent.

Patented Apr. 12, 1921.

Application filed January 4, 1917. Serial No. 140,508.

T 0 all whom it may concern:

Be it known that I, Emvns'r HoPmNsoN, a citizen of the United States,residing in New York city, county of New York, and State of New York,have invented certain new and useful Improvements in Methods of MakingMotor-Vehicle Tires, of which the following is a full, clear, and exactdescription.

The present invention relates to vehicle tires made of rubber andfibrous materials and particularly to pneumatic tires of heavy strongconstruction having a thick wall structure such as are necessary formotordriven vehicles. Further, the object of the invention is to providea new tire of very much improved quality by means of a new method ofconstruction and apparatus for accomplishing the desired results.

The present application is a continuation in part of the subject-matterset forth in appgication Serial No. 84,565, filed by me arch 16, 1916,method and apparatus for building pneumatic tires for automobiles, andapplication Serial No. 84,955, filed March 17, 1916,, pneumatic tiresand method of makino the same.

Tires far motor-driven vehicles are now usually made by forming orshaping strips of fabric, whether woven or consisting of parallelthreads mainly held together by rubber, on a heavy metal core ofsubstantially the shape of the cavity of the tire casing when inflatedon the wheel -with which it is designed to be used. After all theelements going to make up the tire casing have been assembled on such acore, it is placed while still on the metal core within outer moldmembers and subjected to great pressure by means of a hydraulic press ina closed chamber which is heated to the desired temperature for thenecessary eriod of time to effect vulcanization.

'here are variations of this method in practice, but in every case thefabric or threads or cords which constitute the carcass of the tire areformed on a metal core of the she e of the tire cavit In all cases wheret e fabric is applie in circumferential strips there is no tension onthe threads during vulcanization and the path of any given thread overthe core is not the shortest path from edge to edge but merely thevariable haphazard result of shaping a flat strip of fabric from thecrown or periphery of the core to the edges.

By my invention strain resisting elements or threads ma be formed into amulti-ply carcass shape like a pulley band in such manner andarrangement as to obtain, precisely, any desired condition of tension inthe threads in the finished tire. \Vhile the threads of any one layer orply are under substantially the same tension, it is possible to have thethreads of one layer relative to the threads of another layer underequal or unequal tension. And further, by varying the width of thelaminations or strips of the strain resisting threads, the tension onall of them in the finished tire may be governed to conform to thedictates of the best practice. I This same result may be obtainedwithout varying the width of the strips by changing the angles of thethreads in all the plies.

In actual practice I preferably lay separate plies of thread fabricsuccessively on each other to form a pulley band, the angles of thethreads of succeeding plies having been predetermined with respect to agiven tire cavit form the pulley and into the form and size of tirecasing with respect to which the calculations of the angle variationshave been made and so that, at such size and shape of tire casing allthe threads of all the plies are under similar conditions of tension inthe finished casing before it is inflated for use, and the tire casingwhen inflated for use will not substantially increase its di' mensions.

I will first explain the principle on which the carcass of the tire isbuilt.

In Fig. 1 the dotted lines indicate a strip of fabric of parallelthreads. In this strip the line A B is one of the threads and coincideswith the hypotenuse of the rightangle triangle A B C of which B C is thebaseand A C the vertical side. If a strip of fabric like thatillustrated in Fig. 1 be laid around a drum illustrated diagrammaticallyin plan in Fig. 2 (actual construction explained hereafter), each of thethreads, for instance A B, will be in contact with the face of the drum,the vertical side A C becoming the circumferential distance A C whilethe base B C, being the width of the strip, will be maintained. Now inactual practice this strip of fabric and the number of superposed pliesnecessary to give the desired strength, are caused to assume the shapeof a. pneumatic tire casing by liftso that it is possible to p ing thecentral portion throughout the entire circumference and movin the ed estoward each other. But considering t is action as applied only to onestrip and referring onl to one thread A B in order to clearly exp ainthe principle involved, the points A and B will be moved to A B and thethread A B will take (ap roximately) the path of the dotted line a inig. 2. Now assume the tire cavity to be represented by the core shown incross-section in Fig. 3, I have foundthat in a 36 x 4% inch tire thethread A B with an angle of fifty degrees (50) to the base B C andconsidered as the hypotenuse of a rightangle triangle, must have a basemeasuring thirteen and three quarter (13%) inches in order that it maylie in contact with the surface of the core while maintaining thecircumferential distance A C which is e ual to the vertical side A C.The thread A is shown in dotted lines in Fig. 5 in contact with the surface of the core. But the surface of the same core from edge to edge, ona ri htangle section is only ten and one-half (1025 inches, so that ifthe base B C were a thread it would be three and one-quarter (3%) incheslonger than necessary to extend from edge to edge over the core at.right angles. f therefore, weshould lay a strip of fabric with thethreads lyin at an angle of fifty degrees (50) to the iiase like that ofFi 1 on a drum, and then build up on this p y any imaginary pliablematerial to the proper thickness and then we should lay a strip offabric whose threads lie at right angles to the edges of the strip likeB G and then move the edges of such a composite band toward each otherto the points A B indicated in Fig. 2, the thread A B would lie incontact with the. core without tension and the thread B C would likewiselie over the increased surface from edge to edge without tension. Thesupposed construction is illustrated in Fig. '4 1n flat cross-sectionand in tire shape in Fig. 3, the filling material being designated bythe letter E. Therefore, it follows that after we have laid the firstply in position we may lay a second ply of threads directly over thefirst ply around the drum at such an angle approaching the rightangle ofthe thread B C so as to exactly compensate for the increase in thecircular distance resulting from the application of the first ply whenthe plies are moved into tire shape, andsq that the threads of thesecond ply will lie over the first ply in the same tension condition asthe threads of the first ply lie over the core while maintaining thesame lateral width or base measurement B C. I have indicated suchathread by the line F G in Fig. 1, this second ply thread beingrlaid atan angle of forty-nine and one-half (495) degrees,

which is substantially correct for a 36 x 4!;

nine and one half (49:1

inch tire casing built up of plie s of fabric consisting of thread andrubber of .047 inch thick strip.

In the drawings Figures 1, 2, 3, 4 and 5 are diagrammatic viewsillustrating a principle of operation involved in the invention.

Fig. 6 is a side elevation of a building drum.

Fig. 7 is a view illustrating the building drum in section along theline 77, Fig. 6.

Fig. 8 is a plan view showing the arrangement of the superposed stripsof fabric of the carcass before turning the edges over the retainingwires.

Fig. 9 is a plan view showing the edges of the fabric of the carcassturned over the retaining wires and the various elements of the treadconstruction applied.

Fig. 10 is a cross-section of the completed casing in pulley-band form.

Fig. 11 is a view, partly in side elevation and partly in section,illustrating the forming device, while Figs. 12 and 13 are de tailedviews of the retaining rings shown in Fig. 11.

Fig. 14 is a cross-section of a moId-inclosing a tire and tube, whileFig. 15 is an enlarged detailed cross-section of one edge of the flatpulley band.

Fig. 16 is a diagrammatic view of a sheet of fabric illustrating thecutting of the fabric strips.

Referring now to the actual construction of a tire embodying myinvention, I take a sheet of fabric consisting of parallel threads whichmay be held together simply by un vulcanized rubber or by a weak weftthread woven across the main warp threads at intervals of approximatelyhalf an inch, which is an ordinary method of holding the warp threadsparallel. Assuming such a sheet of fabric properly rubberized either byskimcoating or solutioning or by any other desired method, I cut thesheet into strips at the desired angles.

I will now describe the building of a 36 x 4-5 inch tire casing, thecarcass of which is made up of six plies of thread fabric of .04 inchthickness, attached to or supported by a sheet of rubber of .007 inchthickness.

The first step is to cut the various plies of the desired width and atthe predetermined angle. I have found by actual measurement that with atire casing of this size and using the thread fabric and rubber -ust before indicated, if the threads of the rst ply (that is the innermostply) lie at an angle of fifty degrees (50) to the axis of the drum, or,what is the same thing,at an an le of fifty degrees (50) to a line'atrig t angles to the longitudinal center of the strip, the angle of thesecond pl should be fort degrees to c axis; inthe third ply forty-nine(49) degrees; in the fourth ply, forty-eight and one-half (48%) degrees;in the fifth ply forty-eight (48) degrees; and in the sixth lyforty-seven and one-half (47%") degrees. hese figures are not absolutelycorrect but practically correct and such as I have used in actualpractice. I will hereafter describe how I have arrived at these variousangles. To obtain strips with the proper angles the full width of thefabric is out along lines which are the complements of these desiredangles; that is, the first strip will be cut at an angle of forty (40)degrees to the edges of the fabric, the sccond ply strips will be cut atan angle of forty and one-half (40. degrees, the third at an angle offorty-one (41) degrees, the fourth at an angle of forty-one and one-half(419 degrees, the fifth at an angle of forty-two (42) degrees, and thesixth at an angle of forty-two and one-half (421 degrees. The variousstrips are illustrated in Fig. 16, which shows in dotted lines a pieceof fabric with the various strips outlined thereon. Of course inpractice all the fifty degree (50) strips will be cut successively andthen all the forty-nine and one-half (49%") degree strips, then theforty-nine (49) degree strips, and so on, so that there will be no wastein cutting strips at different angles from the same iece of fabric. Itwill also be understood t at the width of the strips will vary, as theedges of the fabric when laid around the drum will be stepped, eitheroutwardly or inwardly, as hereafter explained.

Assuming we have a supply of the necessary strips of fabric, I takestrip number 1,

illustrated in F ig. 16, and lay it around a.

collapsible drum 13, which 518 suitably mounted on a pedestal 14. i Theends of the strip are abutted together so as to form a complete handwithout lap as the last thread at the end of the strip joins up to thefirst thread of the strip by the turning of the drum. In Figs. 6 and 7 Ihave illustrated a form 'of collapsible drum suitable for the purpose.It is unnecessary here to describe the drum construction in detail. Inpractice the drum is half way collapsed before the application of thefirst ply. I next apply strip number 2 with the threads running in theopposite direction, joining the endsof the stripby abutting them just aswas done with the first ply. I then place a strip of "separating fabric15 over the edges of these two plies before laying on the next ply, toprevent adhesion of the edge ortions to the strip of fabric next appliein order to facilitate the lat-er folding over operation. I then applythe layers numbers 3 and 4 and then interpose another strip ofseparatingmaterial 16 at the edge portions and finally step is to place thecircumferential wires 17 lay on the plies 5 and 6. The next in position.To do this, the drum is completely collapsed inforder that the wires maybe readily placed over the superposed plies into position one from eachside of the drum. Once the wires are located in position, the drum isexpanded so as to tightly press the layers of fabric against the wires17. Then the edge portions of the various layers are folded over thewires from eachside, two plies being folded over at a time. Thisoperation of folding over two plies at a time ispermitted and made easyby the inte osition of the separating strips 15 an 16. After the fifthand sixth plies have been folded over, the separating strip 16 is thrownto one side and plies 3 and 4 are folded over. Then the separating stri15 is removed and the first two plies placed in position on the drum arealso folded over the wire. The 1 next operation is to apply a. layer ofrubber 7 (illustrated in Fig. 9). This rubber strip 7 does not extendfrom edge to edgeof the casing but only across the tread portion and isin fact what is known as the cushion stock in the regular constructionof tire. Over this rubber layer 7 I place two plies of thread fabric 8and 9, the threads of these plies being spaced apart and serving as thebreaker strips. I next apply a layer of rubber 10 similar to the layer 7and then apply two more breaker layers of fabric 11 and 12 and finallapply the tread rubber 12. The threads of the breaker layers 8, 9, 11and 12 are laid at angles of 44, 4:31P, 42, and 41% to the axisrespectively. Instead of the breaker strips here referred to, theordinary square woven bias-cut fabric may be used and the width of thesebreaker strips may be varied as desired. The casing is now complete inpulley band form as illustrated in Fig. 10.

The next operation is to cause the pulley band to assume approximatelthe U-shape of the finished casing. This do by lifting the center andsimultaneously forcing in the edges, which operation I preferablyperform in the manner and by means of apparatus illustrated in Figs. 11,12, and 13, a though any other desired manner and means may be availedof.

Referring to Fig. 11, the framework of the machine consists of twouprights 18 and a cross-piece 19. Extending from the crosspiece to thebase are two threaded rods 20, each of which has secured to It a bevelgear 21, meshing with a bevel gear 22 on shafts 23', each of whichshafts carries a. bevel gear 24, driven by bevel gear 25 which isconnected by any suitable means to a. source of power. Centrally locatedbetween the uprights is a cylinder 26 on which rests a removable ring27, which in turn supports a removable ring 28. The ring 27 is providedwith a central circumferential channel 29 in which is located aninflating suificidnt air pressure is a tube 30 having a valve 31. Twoforcing rin 32 are provided, each of which is carrie on arms 33 having athreaded engagement with the rods 20.

The operation of causing the carcass to be shaped to the form of thetire casing from the flat pulley band form is as follows: The rings 32are in their positions farthest apart from each other (the position ofthe up r ring indicated in dotted lines in Fig. lll and the .rin 27 isresting on the cy inder 26 while t e ring 28 is. entirely removed. Thisleaves enough space between the top of the ring 27 and the lower edge ofthe ring 32 to permit of the easy inse tion of the ulle band casing. Itwill be understood t at t e ring 27 carries the tube 30 ready forinflation at the proper time. The lower flange with its retaining ringare then placed -in position. There are two flange and retaining rings,one to co-act with each edge of the casing. Each of these devicescomprises an endless flange ring 34 having a shelf or inwardly extendingortion 35 and a slotted outwardly exten g portion 36. Each of theretaining rings consists of a broken rin of spring metal 36 havingpro'ections 37 beveled on their lower faces an extending into the slotsin' the outwardly extending portion 36 of the flange 34.

The pulley band casin is now placed in position, as lndicated in ig. 11.Then the ring 28 is laced in position resting on ring 27 and fina ly theupper flan e and retaining ring are placed in position. ower is nowapplied togear 25 causingthe rods 20 to turn, 32 toward each carryin theforcing rm other. lhis brings the jings 32 into the sitions shown infull lines in Fig. 11, the inward extension 35 of each of the flanges 34being forced somewhat under the edges ,of the pulley band casing so thatthere is a clearance between the inner surface of the pulley band casinand the outer surface of the rings. The rther movement of the forcing rm32 is accomplished simultaneously with'the admission of air underpressure to the inflatable tube 30 which lifts the central portion ofthe pulley band as the forcing rings 32 move the ed of the easing towardeach other to a circumferential line on each side of the channel 29coinciding with the slots 39; and when projections 37 of the retainingrings come to position .over these slots the snap into engagement withthe slots. to 100 the fla in osition. itte 'to the inflatable tube tocause the casing to assume tire she as shown in dotted lines in Figjll.e flanges 34 being locked to the ring 27 by the engagement of theprojections 37 in the slots 39, the gear 25 I is now reversed to moveapart the forcing 05 range 32; then the ring 28 is lifted off theannular base 40 for the tire (Fig. 14), a

bull ring 41, outer mold members 42, and straps 43, these straps 43occurring at intervals throughout'both the inner and outercircumferences of the mold and serving to keep the mold members 42together against the internal pressure. In Fig. 15 I have shown insection a modification of the edge construction of the casing, the firstply in this instance bein the narrowest. Of course various modi cationsof this sort may be made if desired.

To return for a moment to the pulley band casing it should be notedthatfor the ,size of tire (36 x 4%"), the buildinfg of i my which I havespecifically described, first ply consists of parallel threads at anangle of 50 to the axis, the base B C (F i 1) must be 13% inches inorder to give su clent length to the threads (A B of Fig. 1 forinstance) to pass over the desired core or rather casing cavitunstretched and with the circumferential istance A C (Figs. 2 and 5).But I cut the first ply fifteen and one-half (15%") inches wide, andsucceeding pliesfifteen (15") inches, fourteen and one alf (14%")inches, fourteen (14" inches, thirteen and one-half (13%") inc es, andthirteen (13") inches, andlay the plies around the drum with theircenters coinciding, and then place'the side wires 17 on top of the lastply eleven and one-quarter (11%") inches apart (Figs. 8, 9, and 10).Aftenthe portions of the plies extendin beyond the side wires 17' havebeen folde over, a portion of all the plies eleven and one-quarter(111") inches wide is held by the side '17 to form the carcass durin theforming process above described. Now i the threads are tolie' over thedesired cosing cavity without'tension, the lateral distance betweenwires must equal the base B O which is thirteen and three-quarterformation longitudinally while the width of the pulley band or thedistance between retaining wires is diminished during the formation ofthe tire from the pulley band form. And this actually occurs inpractice. The distance between the wires of the pulley band in the tiresspecifically considered is 11;, inches while in the finished form of thesame tire measured over the cavity of the casing, it is only 10%. Thisof course comes about because the threads of each ply are compelled tomove into a (generally speaking) spiral path in which they lie on thetread portion at an angle greater than the original angle of the flatstrip. That is to say, in the forming operation the portions of thethreads adjacent the bead members and along the sides tend to preservetheir angular relation to the axis of the pulley band more than theintermediate or central portions of the threads over the tread of thecasing. This is diagrammatically and rou hly approximated in theillustration of ig. 2. As a matter of fact the threads of the first plywhich are at an angle of on the flat, take on an angle of 59 on thetread portion of the finished tire. Again, the tire casing in its pulleyband form has a diameter of twenty-seven (27) inches while the diameterat the periphery of the outer ply of the carcass in the finished tire(leavin the tread rubber out of consideration) is t irtyfive (35)inches; or a difference of twentyfivo (25) inches in circumference. Onemight expect therefore that the threads on the tread portion of thefinished tire would be spaced farther apart than in the pulley handform. But this is not so. In the forming process the threads on thetread portion have all passed through a parallelogram movement toproduce the increase in angle just spoken of and they are in fact closertogether on the tread of the finished tire than in the pulley band form.

Going" back now to the placing of the tire in the vulcanizing mold itwill be apparent from the explanation immediately foregoing that theformation by inflation before dcscri ed has not caused the casing to assumo its final dimension-a so that when it is placed in the moldconsisting of the mold members 4 2 and rings 40 and 41 it does not fillthe mold cavity. It is not necessary to detail the manual processes oftaking the casing oil the ring 27 and placing it in the mold, except tosay that an air-bag or inner tube (either green, semi-vulcanized orfully vulcanized) is placed in the casing and fluid pressure introducedinto the tube or air bag. In actual practice I use a semicured tube 44having substantially the dimensions shown in dotted lines in Fig. 14which approximates the cavity of the casing after it has been taken offthe ring 27 and the bull-ring 41 inserted and before the introduction offluid pressure in the tube 44.

In using a tube to inflate the casing during vulcanization, I accomplishtwo distinct improvements in that I save the expense of air-bags whichordinarily last only five or six vulcanizations and at the same timesave the ex ense of a portion of the vulcanization of the inner tube andobtain a much improved tube in that it is exactly shaped to the tirecavity. In detail I take a tube which has been semi-cured onlysufliciently long to partially set the joints while leaving the outersurface slightly sticky. I then apply one of various substances to theouter surface of the tube and the inner surface of the casing to keepthe tube separate from the casing during vulcanization. For this purposeI have successfully used glycerin, talc, graphite, starch, powderedmica, and the paint powder known as aluminum bronze. I prefer the lastmentioned because it leaves the outer surface of the tube and the innersurface of the casing with a beautiful silvery appearance and will serveas a lubricant between the casing and tube when in use. After thecoating process the tire and casing are assembled and placed in themold. I then introduce fluid preferably at a pressure of one hundredeighty (180) pounds to the square inch and place the mold in a heaterfor a predetermined period, depending on the character of the rubbercompounds used. I prefer to use CO as the fluid pressure medium, althouh other mediums may be used. During t e vulcanizing process the internalpressure of course increases, due to the Vulcanizing heat which iscommonly about 280 F. The heat also acts to soften the rubber and hencethe internal pressure finds less resistance to its forming action of thecasing during the vulcanizin process than when the casing is cold, sothat the casing is caused to be pressed firmly against the inner surfaceof the mold members and the threads of the arcass are tensioned to thedesired degree. Upon the completion of the vulcanizing oporation thecasing and tube are taken out of the mold and separated from each other.

In the present application, while the entire process and apparatus havebeen described in order that a full understanding of the invention maybe had, only certain portions are made the subject of the claims,leaving other portions to be claimed in other ap licationsome of theadvantages of the invention are as follows: It permits of the formationof the casing of an automobile tire in pulley band form notwithstandingits necessarily thick heavy construction. This in itself is of greatimportance for various reasons. The tire may be built much more quicklyand cheaply than by any other process. The apparatus is much simpler,cheaper, and lighter than is necessary in any other procsee. The usualheavy core and necessity for 7 side wall which in turn com rises sionindependent of any .from inflation in use.

corres onding angles.

its manipulation are entirel done away with. The threads of the ifierentplies may be sucessively laid at such angles as to exactly compensatefor increase in size resulting from the application of previous plies sothat the inflating process may act to she e the pulley band into tireshape. It ma es it ossi le to so locate the side rings as to re uce inthe vulcanized tire a carcass in which the threads are actually undertenstretch resulting All the threads lie along substantiall theirshortest paths from edge to edge. T is results in a minimum of internalstrains and stresses under the flexing action in use, so that the pliesdo not separate from each other. It ermits of laying the threads at-anydesire angle. That is the first ply may be laid at and so on, succeedingplies being laid at his is very important, ecause the shape of thefinished tire under inflation in use largely depends on the angles atwhich the threads are laid, the genera proposition being that thegreater the angle of the threads to the axis of the tire the flatter thetire will be on the tread and the less the outward ull on the sidewires. And in a tire in which the natural effect of inflation results ina flattened tread and correspondingly greater rounded shape to the sidewalls, a greater'wearing surface is obtained on the tread, and theflexing point in the side wall is not localized but distributedthroughout a greater length of a much gfeater length of threads. 0illustrate, t e specific tire the building of whichl have described,when molded in a mold designed for an ordinary tire, showed a decreaseof one inch in circumference on the periphery and an increase in lateralcross-section at the widest point of one-half inch after inflation ascompared with dimensions taken before inflation. This efiect is enhancedin a tire made up of plies of fabric in which the threads lie at aterangles to the axis than in the tire refldfred to. 'In a tire madeaccording to my invention, the carcass flexes as a unit. Again, there isabsolutely no waste in the building operation. The plies are cut toexact size and require no trimming. Another feature that ma he referredto is the fact that any co guration .of the tr'eadrubber may be obtainedin a single vuleanizing operation as against the necessity forseparatevulcamzation of tread and carcass and an additional vulcanizingoperation to unitethe two which obtains in the ordinary rocess ofmanufacture where an anti-ski tread is desired. Incident'ally, the costof vulcanizing the inner tube is lessened and a better tube obtained.

Ina tire made'by the ordinary process of smoothing a flat strip over acore the shape of the tire cavity, the threads of outwardly succeedingplies are longer than the threads of preceding plies and the threads ofall the plies are distorted out of their shortest paths, whereas in mtire the threads of succeeding plies are s orter than in preced: ingplies and all the threads of all the plies lie in substantially theirshortest paths, by an amount exactly determined by the angle at whichthey lie when flat which will allow all the threads to take theirnatural and substantially shortest plaths from edge to edge and when intire s ape to be all under the same condition of stretch. It will beseen too, that as all the plies are laid on the drum at the diameter ofthe ed es of the casing, there is a, great saving in t e amount offabric used, as each pl is shorter and because of the unity of actionbetween all the plies, fewer plies are needed. Again the threads offabric are closer together at the tread portion where relative rigidityand resistance are required and are spaced farther apart and theintervening spaces filled with rubber at the side portions whereflexibility is desirable.

If the threads in the fabric strips are laid at a still greater angle,that is to sa commencing in the first ply with threa s at an angle of 60to the axis, I have found that the side wires need not be inextensible,but in lieu of inextensi le wires a simple winding of cord'may be usedto define the edges and form a folding line for the projecting edges ofthe. fabric strips going to make up the carcass. It has been shown thatthe width between the edges of the tire casing when in the pulley bandform, is controlled by the angle of the threads in the various plies, sothat with a pulley band in which the threads of the first ply are at anangle of 60, the width must be still greater than that indicated. Theforming action diminishes this lateral distance of the pulley band tothe desired lateral distance necessary for the particular tire cavity inmind, and therefore the threads move closer together. This imposes thenecessity that the threads shall be spaced sufficiently apart in theulley band form to permit this action to ta e place. In such a tire theed e of the casing is extensible when unin ated so that it may bepriedover the side flange of a one-piece rim. The result of inflationto. riding pressure is to cause the threads to so act onthe edges of thetire casing as to bind them to the surface of the Tim and cause ahugging action and there is no outward pull on the edges of the casing.

I may say that it is important to determ ne the angles of the threads insucceeding plies with substantial accuracy, because,

mathematically considered, there is only one angle variation betweenplies which will permit of obtaining exact compensation in any given plyfor the increase in circumference in underlying plies resulting fromshaping plies of the same width from pulley band form to the form of atorus. This ma be determined mathematically, but the ca culations arevery complex. To enable others to practice the invention, the angles maybe determined in the following manner: Having determined the size oftire desired, the number of plies of fabric, thickness of cushion stockand thickness of tread stock, as also the desired inflated cavity, Ifirst make an arc of a core of the cross-sectional shape and size ofsuch desired cavity; then let us say we decide that the threads of ourfirst ply shall be at an angle of 50 flat, we first find what length ofa thread at that angle will be necessary to pass from edge to edge ofthe core. A simple apparatus is desirable for this empirical method ofdetermining the angles. Take a portion of a wide drum of the diameter ofthe edges of the core, lay the thread on the drum, pre serving the 50angle when flat, which simply means that the circumferential distancebetween the ends of the thread shall be the same as the altitude A C(Fig. l) for a given length of thread. Secure each end of the thread toclamping devices, both of which are capable of being moved to and awayfrom the center of the face of the drum and one of which is capable ofbeing moved circumferentially. Then place the core along the center ofthe drum and manipulate the thread and thread-holding devices by movingthem toward and away from the core (and one of them circumferentially)until a circumferential distance between the two ends of the thread isobtained which coincides with the altitude of A C of Fig. 1 for a lengthof thread (hypotenuse A B of Fig. 1) whlch it has been found willexactly lie over the core from edge to edge and which when laid on aflat surface will lie at the desired angle of 50. The base B C will thenbe measured. A second core is now substituted for the first core, thesecond core being a facsimile of the first core augmented in size by anamount equal to the first ply. Now we go through the same process tofind the angle of the second ply, always maintaining the lateraldistance or base measurement C, because, clearly, the problem requiresit, as the retaining wires in the actual construction define the samelateral distance for all plies. This operation is repeated for each ply.

Of course various modifications ma be made without departing from thespirit of my invention. For instance, I have described the entire casingas made fiat. If desired, only the carcass need be made fiat and thedesired tread construction applied plies of rubberized fabric, becausethat feature in my opinion, is essential to obtaining the best results;but it will be apparent that the method of construction of the tirecasing here described may be utilized in a thread fabric tire in whichthe threads of the several plies are of the same angle, as also in atire casing made of woven fabric. While I have specifically describedand illustrated a straight side tire casing having an inextensible wirelocated in each edge, the casing may be made with an extensible clencherhead, or may be of the quick de' tachable type, or may be made with astraight side but without any wire in the edge, so that it will beextensible. In the case last mentioned, the threads will be of theconstruction referred to in the specification, in which the threads arelaid at a comparatively great angle (say 65) to the axis of the tire, sothat the effect of the internal pressure will not tend to lift the tirefrom the side flanges of the rim.

When in the claims I speak of a tire casing made of a plurality ofstrips of rubberized fabric formed into an unvulcanized multi-ply pulleyband, I mean by the words plurality and multi-ply to refer to aCOIlS'tIllclJlOfi composed of two or more plies.

Having described my invention, what I claim and desire to protect byLetters Patent is:

i. In the method of making a tire casing for motor vehicles, the stepsof laying a plurality of separate strips of rubberized fabric on eachother to form an unvulcanized multiply pulley band folding over theedges of said pulley ban shaping the unvulcanized pulley band to tireform while maintaining the order of the plies and finally vulcanizing.

2. In the method of making a tire casing for motor vehicles the steps ofsuperposing a plurality of previously formed strips of rubberized fabricto form an unvulcanized multi-ply pulley band with its edge portionssubstantially in the plane of the pulley band, applying a retainingmember to each of said edge portions, giving tire form to the pulleyband before vulcanization by distending the central portion and causingthe edge portions to move toward each other and in such movement to turnfrom the plane of the pulley band to substantially final ositionsubstantially at right angles to sai plane with the axis of the pulleyband than the threads of a preceding ply, placing a retaining memberadjacent each ed e of the pulley band, folding the edges of t e pulleyband over the retaining members, giving tire form to the pulley bandbefore vulcanization, while maintaining the order of the plies, andfinall vulcanizing.

4. in the method of making a tire casing for motor vehicles, the stepsof superposing a plurality of separate rubberized fabric plies to forman unvulcanized Inulti -ply pulley band, folding over the edges of thepulley band, forming the unvulcanized pulley band into tire sha e whilemaintain- 25 ing the order of the plies, and afterward vulcanizing.

5. In the method of making a tire casing for motor vehicles, the stepsof wrapping a plurality of separate rubberized fabric =0 plies around adrum to form an unvulcanized multi-ply pulley band, folding over theedges of the pulley band, forming the un- Vulcanized pulley band intotire shape while maintaining thelorder of the plies, and afterwardvulcanizing.

6. In the method of making a tire casing for motor vehicles, the 'ste sof superposing a plurality of rubberize 1 fabric plies to form anunvulcanized multi-ply pulley band, forming the unvulcanized pulley bandinto tire shape while maintaining the order of the plies, bysimultaneously lifting the pulley band by pressure radially appliedalong its central circumferential portion 45 sand moving the edgestoward each other, and

there securing them and afterward vulcanizing.

7. In the method of making a tire casing for motor vehicles, the stepsof superposing 0:3. plurality of separate rubberized 'fabiic plies-t0form an unvulcanized multi-ply pulley band, the angle of the threads ofoutwardly succeeding plies progressively varying toward parallelism withthe ax1s,'-forming the unvulcanized pulley band into the shape whilemaintaining the order of theplies, and vulcaniaing.

' 8. In the method of making a tire casing for motorvehicles, the stepsofsuperposing 1M), plurality of rubberized fabric plies around a drum toform an unvulcanized multi-ply ulley band, placing a retaining member ajacent each edge of the pulley band, folding the edges of the pulleyband" taining the order of the over the retaining member, forming theunvulcanized pulley band into tire shapewhile maintaining the order ofthe plies, and then vulcanizing.

9. The method of making a tire casing for motor vehicles which consistsin superposing a plurality of previously' formed rubberized fabric liesto form an unvulcanized multiply pul ley band with its edge portionssubstantially in the plane of the pulley band, applying a retainingmember to each of said edge portions, then applying a layer of treadrubber to the pulle band, forming the unvulcanized pulley and intotireshape by distending the central portion and causing the edge portions tomove toward each other and in, such movement to turn from the plane ofthe pulley band to substantiallyfinal position substantially at rightangles to said plane and extending toward the center of the casing,while maintaining the order of the plies, and finally vulcanizmg.

10. The method of making a tire casing for motor vehicles which consistsin superposing a plurality of rubberized fabric plies to form anunvulcanized multi-ply pulle band, the angleof the threads of outward ysucceeding plies progressively varying toward parallelism with the axisof the pulley band, forming the unvulcanized pulley band into tire shapewhile maintaining the order of the plies, andat the same time stretchingthe threads and finally vulcanizing the casing while the threads are instretched condition.

11. The method-of making a tire casing for motor vehicles which consistsin superposing a plurality of rubberized fabric plies over a drum toform an unvulcanized multiply pulley band, the angle of the threads ofoutwardly succeeding plies progressively varying toward parallelism withthe axis of the pulley band, folding over the edges of the pulley band,forming the unvulcanized pulley band into tire shape While mainlies, andstretching the threads and final y vulcanizing.

12. The method of making a tire casing for motor vehicles which consistsin superposing a plurality of rubberized fabric plies over a drum toform an unvulcanized multiply pulley band, the angle of the'threa'ds ofoutwardly succeeding plies progressively varyin toward parallelism withthe axis of the pn ey band, placing retaining members adjacent each edgeof the pulley band, fold ingthe edges of the pulley band over theretaining members, forming the unvulcanized pulley band into tire sha ewhile maintaining the order of the p 'es, and finally vulcanizin 13. Themethofof making a tire casing for motorvehicles which consists insuperposing a plurality of rubberized fabric plies over a drum to form apulle band, the angle of the threads of outwar ly succeeding plies proressively varyin toward parallelism with t c axis of the pul ey band,placing retaining members adjacent each edge of the pulley band, foldingthe edges of the pulley band over the retaining members, forming thepulley band into tire shape bylifting the central ortion by means of aninflatable tube and simultaneously movln the edges toward each other andfinally vu canizing. I

14. The method of making a tire casing for motor vehicles which consistsin su erposing a plurality of rubberized fa ric plies over a collapsibledrum to form a pulley band, the angle of the threads of outwardlysucceeding plies progressively varying toward parallelism with the axisof the ulley band, placing retaining members a jacent each edge of thepulley band, folding the edges of the ulley band over the retainingmembers, col apsing the drum and removing the pulley band, forming thepulley band into tire shape by lifting the central portion by means ofan inflatable tube and simultaneously moving the edges toward eachother, ap lying fabric to form the trea portlon of the casing andfinally vulcanizin 15. The method of making a tire easin for motorvehicles which consists in superposing a plurality of previously formedrubberized fabric plies to form an unvulcanized multi-ply pulley bandcarcass with its edge portions substantially in the plane of the pulleyband, a plying a retaining member to each of sai edge plying cushionrubber, a brea fabric and the tread rubber to band, forming theunvulcanized pulley band into tire shape by distending the centralportion and causin the edge portions to move toward each ot er and insuch movement to turn from the lane of the pulley band to substantiallyfinal position substantiall at right angles to said plane and exten ingtoward the center of the casing, while maintaining the order of theplies, and finally vulcanizing.

16. In the method of making a tire casing for motor vehicles, the stepsof la ing a plurality of separate strips of rub erized fabric on eachother to form apulley band, folding over the edges of said'pulley band,shaping the pulley bandto tire form by or strip of the application offluid pressure to the ina side thereof and finally vulcaniz' 17 In themethod of making a tu-e casing for motor vehicles, the steps of laying aInrality of separate strips of rgbberized bric on each other to form apulley band, folding over the edges of said pulley band, shaping thepulley band to tire form by rubber and ortions, ap-

the pulley inflating an expansible air bag within the band, and finallyvulcanizing.

18. In the method of making a tire casing for motor vehicles, the stepsof wrapping a plurality of separate rubberized fabric 188 around a drumto form a pulley band, olding over the ed es of the pulley band, formingthe pulley and into tire shape by the application of fluid pressure tothe inside thereof and afterward vulcanizing.

19. In the method of making a tire casing for motor vehicles, the stepsof wrappin a plurality of separate rubberized fabric Iies around a drumto form a pulley band, olding over the edges of the pulley band,formflating an expansible air bag within the band and afterwardvulcanizing.

20. The method of making a .tire casing for motor vehicles whichconsists in superposinga plurality of rubberized fabric plies to form apulley band, the angle of the threads of outwardly suoceedinfi plies progressively varying toward para e ism with the axis of t e pulle band,forming the pulley band into tire s ape and at the same time stretchingthe threads by the application of fluid pressure to the inside of theband and finally vulcanizing the casin while the threads are instretched condition.

21. The method of making a tire casing for motor vehicles which consistsin superposing a plurality of rubberized fabric plies to form a pulleyband, the angle of the threads of outwardly succeedin pliesprogressively va ing toward para lelism with the axis of t e pulleyband, forming the pulley band into tire shape and at the same timestretching the threads by inflating an expansible air bag within theband and finally vulcanizing the casing threads are in stretchedcondition.

22. The method of making a tire casing for motor vehicles which consistsin superposing a plurali? of rubberized fabric plies over a drum to orma pulley band, placin retaining members adjacent each edge 0 the pulleyband, folding the edges of the pulley band over the retaining members,forming the pulley band into tire shape by lifting the central portionby means of an inflatable tube and simultaneously moving the edgestoward each other and finally vulcani'zing.

23. In the method of making a tire casing for motor vehicles, the stepsof forming a pulle band of rubberized fabric in which the t reads ofsuch fabric lie at an acute angle to the edges of the pulley band,for-min such pulley band into tire sha e by ap ying ressure radiallyalon t e centra circum erential ortion thereo and forcing its edgestowar each other, at the same time decreasing the ce on a line mg thepulley band into tire shape'by inwhile the i passing from edge to edgeover the fabric of the pulley band.

24. The method oi making a cord-tire easing which consists iniorming anannular fiat band of diagonally-extending cords, placing a pair ofbeadc0re rings t ereover, overlayin said band and rings with a secondannu ar fiat band of rubberizedcords which extend diagonally .across thecords of the first band, inclosing the bead-core rings between themargins of said bands, shaping the raw carcass substantiall to itsultimate form by distending the mid le ortion and drawing the beadscloser toget er, and finishing and vulcanizing the casing.

25., The method of making a cord -tire casin which consists in formingan annular flat and of diagonally-extending cords, placing a pair oiinentensible bead-core rings thereover, overlayi said band and rin witha second annu ar flatband of rub erized cords which extend diagonallyacross the cords ofthe first band, wrappin the margins of one of saidbands aroun the core rings and overlapping the ma ms of the other bandupon those of the 'rst band, shaping the raw carcass substantially toits ultimate form by distending the middle portion and drawing the beadscloser together, and finishing and vulcanizing the casing. 7

26. That method of makin a tire casing for motor vehicles which incudes, formin a laminated pulley band of rubberize strain resistingelements, incorporating bead members in the pulle band at a distanceapart greater than t width oi the laminations etwecn the beads in thefinished tire, forming the pulley band to approximately tire shape andprior to com plete vulcanization decreasingthe width of the laminationsbetween the beads, and completely vulcanizin 27. That metho for motorvehicles which inc strain-resistin threads into a fabric strip and at aninc ination to its edges plying up the strips to form a ulley banincor-' porating bead members 111 the pulley bend at a distance apartgreater than of the strips between the beads in the fin-t ished tire,formin the pulley band to approximately tire ape and prior to completevulcanization decreasing the width of the strips between the beads.vulcanizing.

28. That method of makin a tire casing for motor vehicles which inc udesbuilding a "plurality of strips of rubberized fabric to form an endlessband, placing bead mermbers at the edge portions of the endless band,distending t e entire endles band circumferential] and thereby pressingit against the bee members, fermin 'the end of makin a tire, casing lessband to approximately tire s ape, and

finally vulcanizing it in finished form.

29. That method of making a tire casing for motor vehicles whichincludes forming strain resisting elements into a multi-pl udes, pinningthe width and completely I pulley band of a predetermined diameter,

relaxing the pulley band, sitioning bead members thereon of a ameterghreeater than said predetermined diameter oft pulley band, expandingthe pulley band and ressing it against t e mg the pulley band toapproximately tire ihape, and finally vulcanizing it in finished orm.

Signed at New York county of New York and State of New York, this 3rdday of January, 1917 v ERNEST HOPKINSON,

bead members, form- DISCLAIMER 1,374,505.--Emest Hopkinson, New York, N.Y. METHOD 0! MAKING MOTOR VEHICLE Tums. Patent dated April 12, 1021.Disclaimer filed June 24, 1936, by the assignee, United States RubberCompany. Hereb enters this disclaimer to claims 16 and 18 of saidpatent.

5 w: Gazelle July 28, 1986.]

